FLORIDA STATE HORTICULTURAL SOCIETY. 
71 
and found that they exhibited the same 
power as Way’s artificial ones. Other 
investigators have shown that the absorp¬ 
tive power bears a close relation to the 
amount of soluble silicates present. That 
is to say the absorption of salts of the 
alkalies, accompanied by the change of 
base, is due chiefly to the presence of 
zeolitic materials in the soil. 
There is besides this purely chemical 
absorption of salts by the soil, a physical 
absorption, which is illustrated by the ab¬ 
sorption of water containing dissolved 
salts, by the organic matter of a muck 
soil; even sand will hold back a limited 
amount of dissolved salts, but the amount 
is in proportion to the fineness of the 
soil, and that it is held in a merely me¬ 
chanical way can be demonstrated from 
the ease with which it is washed out. 
IMPORTANCE OF THE ABSORPTIVE POWER 
« 
OF THE SOIL. 
The importance of this absorptive pow¬ 
er can scarcely be estimated. Houston and 
Goss formerly of the Indiana Station, 
have pointed out that by means of this 
power those mineral ingredients of plant 
food of which most soils contain but lit¬ 
tle, referring more especially to phosphor¬ 
ic acid and potash, are held in a form too 
insoluble to allow of rapid loss by drain¬ 
age, and still soluble enough to answer 
the needs of vegetation, provided the 
store is large enough. This cannot, how¬ 
ever, be said to apply to nitrogen in the 
form of salts of nitric acid, but here na¬ 
ture has made a wise provision for this 
element by binding it in the form of or¬ 
ganic bodies which nitrify but slowly, 
. and by supplying each year a small 
amount from the atmosphere. Houston 
and Goss conclude their discussion of the 
importance of soil absorption with the fol¬ 
lowing statements; ^‘By means of the ab¬ 
sorptive power of soils, the farmer if he 
puts on an excess of potash and phos¬ 
phoric acids as a fertilizer, does not lose 
it, but is able to reap the benefits from it 
in the next year’s crop: If it were not 
for this power the best method for apply¬ 
ing fertilizers would be a much more 
complicated problem than it is at present, 
as it would be necessary to apply them at 
just the proper season and in nicely re¬ 
gulated amounts to insure against loss.” 
PINEAPPLE SOILS LACKING IN ABSORPTIVE 
POWERS. 
Of course Houston and Gross did not 
have in mind such soils as the East Coast 
pineapple soils when they wrote this, for 
we have there just the conditions which 
they say would make the problem of fer¬ 
tilizer application much more complicated 
than it is, and make it necessary to apply 
them at just the proper season and in 
nicely regulated amounts to insure against 
loss. 
We have there a soil which is practi^ 
cally devoid of clay and therefore of sol¬ 
uble silicates; which contains only traces 
of iron, lime and magnesia, and a com¬ 
paratively small amount of organic mat¬ 
ter but which is, on the other hand, 
98 to 99.5 per cent, sand—much of it 
being very coarse sand—hence there are 
wanting nearly all those properties which 
in ordinary soils would effect the absorp¬ 
tion of soluble plant food, and instead of 
being held there in a form suitable for uti¬ 
lization by the plant roots, it is there in 
quite soluble forms, and as the rains come 
it goes down and down into the soil wa¬ 
ters below. Only that portion is stored 
